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Peripheral antinociceptive effects of a bifunctional μ and δ opioid receptor ligand in rat model of inflammatory bladder pain. Neuropharmacology 2021; 196:108701. [PMID: 34256047 DOI: 10.1016/j.neuropharm.2021.108701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 06/09/2021] [Accepted: 07/05/2021] [Indexed: 02/08/2023]
Abstract
There is a need to develop a novel analgesic for pain associated with interstitial cystitis/painful bladder syndrome (IC/PBS). The use of the conventional μ-opioid receptor agonists to manage IC/PBS pain is controversial due to adverse CNS effects. These effects are attenuated in benzylideneoxymorphone (BOM), a low-efficacy μ-opioid receptor agonist/δ-opioid receptor antagonist that attenuates thermal pain and is devoid of reinforcing effects. We hypothesize that BOM will inhibit bladder pain by attenuating responses of urinary bladder distension (UBD)-sensitive afferent fibers. Therefore, the effect of BOM was tested on responses of UBD-sensitive afferent fibers in L6 dorsal root from inflamed and non-inflamed bladder of rats. Immunohistochemical (IHC) examination reveals that following the induction of inflammation there were significant high expressions of μ, δ, and μ-δ heteromer receptors in DRG. BOM dose-dependently (1-10 mg/kg, i.v) attenuated mechanotransduction properties of these afferent fibers from inflamed but not from non-inflamed rats. In behavioral model of bladder pain, BOM significantly attenuated visceromotor responses (VMRs) to UBD only in inflamed group of rats when injected either systemically (10 mg/kg, i.v.) or locally into the bladder (0.1 ml of 10 mg/ml). Furthermore, oxymorphone (OXM), a high-efficacy μ-opioid receptor agonist, attenuated responses of mechanosensitive bladder afferent fibers and VMRs to UBD. Naloxone (10 mg/kg, i.v.) significantly reversed the inhibitory effects of BOM and OXM on responses of bladder afferent fibers and VMRs suggesting μ-opioid receptor-related analgesic effects of these compounds. The results reveal that a low-efficacy, bifunctional opioid-based compound can produce analgesia by attenuating mechanotransduction functions of afferent fibers innervating the urinary bladder.
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Holmes GM, Hubscher CH, Krassioukov A, Jakeman LB, Kleitman N. Recommendations for evaluation of bladder and bowel function in pre-clinical spinal cord injury research. J Spinal Cord Med 2019; 43:165-176. [PMID: 31556844 PMCID: PMC7054945 DOI: 10.1080/10790268.2019.1661697] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Objective: In order to encourage the inclusion of bladder and bowel outcome measures in preclinical spinal cord injury (SCI) research, this paper identifies and categorizes 1) fundamental, 2) recommended, 3) supplemental and 4) exploratory sets of outcome measures for pre-clinical assessment of bladder and bowel function with broad applicability to animal models of SCI.Methods: Drawing upon the collective research experience of autonomic physiologists and informed in consultation with clinical experts, a critical assessment of currently available bladder and bowel outcome measures (histological, biochemical, in vivo functional, ex vivo physiological and electrophysiological tests) was made to identify the strengths, deficiencies and ease of inclusion for future studies of experimental SCI.Results: Based upon pre-established criteria generated by the Neurogenic Bladder and Bowel Working Group that included history of use in experimental settings, citations in the literature by multiple independent groups, ease of general use, reproducibility and sensitivity to change, three fundamental measures each for bladder and bowel assessments were identified. Briefly defined, these assessments centered upon tissue morphology, voiding efficiency/volume and smooth muscle-mediated pressure studies. Additional assessment measures were categorized as recommended, supplemental or exploratory based upon the balance between technical requirements and potential mechanistic insights to be gained by the study.Conclusion: Several fundamental assessments share reasonable levels of technical and material investment, including some that could assess bladder and bowel function non-invasively and simultaneously. Such measures used more inclusively across SCI studies would advance progress in this high priority area. When complemented with a few additional investigator-selected study-relevant supplemental measures, they are highly recommended for research programs investigating the efficacy of therapeutic interventions in preclinical animal models of SCI that have a bladder and/or bowel focus.
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Affiliation(s)
- Gregory M. Holmes
- Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA,Correspondence to: Gregory M. Holmes, Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, 500 University Dr., Hershey, PA 17036, USA. ;
| | - Charles H. Hubscher
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, USA,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, Kentucky, USA
| | - Andrei Krassioukov
- ICORD, University of British Columbia, GF Strong Rehabilitation Centre, Vancouver, Canada
| | - Lyn B. Jakeman
- National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA
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Meijs S, Liao S, Arendt-Nielsen L, Wang K, Cairns BE. The pro-algesic effect of γ-aminobutyric acid (GABA) injection into the masseter muscle of healthy men and women. Scand J Pain 2019; 20:139-150. [DOI: 10.1515/sjpain-2019-0056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 07/11/2019] [Indexed: 11/15/2022]
Abstract
Abstract
Background and aims
Preclinical studies have reported that activation of peripheral γ-aminobutyric acid A (GABAA) receptors may result in analgesia. The current study was conducted in young healthy men (n = 30) and women (n = 28) to determine whether injections of GABA into the masseter muscle reduce pain in a sex-related manner.
Methods
The effect of injection of GABA alone, or in combination with the non-inflammatory algogen glutamate, was assessed in two separate studies. Lorazepam, a positive allosteric modulator of the GABAA-receptor, was co-injected with GABA in both studies to explore the role of this receptor in muscle pain responses of healthy human volunteers. Masticatory muscle mechanical pain intensity was recorded on an electronic visual analogue scale (VAS) while muscle pain sensitivity was assessed by determining the pressure pain threshold (PPT), tolerance and maximal jaw opening (MJO) of the subjects prior to, and again after the various intramuscular injections.
Results
Intramuscular injection of GABA alone was reported to be significantly more painful, in a concentration related manner, than saline control injections, and this pain was further increased by co-injection of lorazepam with GABA. Co-injection of GABA with glutamate was found to significantly increase glutamate-evoked masseter muscle pain in men, but not in women. There was no effect of injections of either GABA alone, or GABA with glutamate, on PPT, tolerance or maximum jaw opening.
Conclusions
Injection of GABA into the human masseter muscle appears to excite nociceptors to produce muscle pain without a longer term effect on mechanical pain sensitivity in the muscle. The findings suggest that GABA-mediated pain in humans is produced through peripheral GABAA receptor activation. The mechanism underlying the sex-related difference in the effect of GABA on glutamate-evoked muscle pain was speculated to be due to a methodological artifact.
Implications
This study was designed to detect analgesic rather than algesic effects of peripherally administered GABA, and as a result, the concentration of glutamate chosen for injection was close to the maximal pain response for healthy women, based on previously determined pain-concentration response relationships for glutamate. This may explain the finding of greater pain in men than women, when GABA and glutamate were co-injected. Overall, the findings suggest that activation of peripheral GABAA receptors in human masticatory muscle produces pain, possibly due to depolarization of the masticatory muscle afferent fibers.
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Affiliation(s)
- Suzan Meijs
- Center for Neuroplasticity and Pain, SMI, Department of Health Sciences and Technology, Faculty of Medicine , Aalborg University , Aalborg , Denmark
| | - Shaojun Liao
- Center for Somatosensory-Motor Interaction, Department of Health Sciences and Technology, Faculty of Medicine , Aalborg University , Aalborg , Denmark
| | - Lars Arendt-Nielsen
- Center for Neuroplasticity and Pain, SMI, Department of Health Sciences and Technology, Faculty of Medicine , Aalborg University , Aalborg , Denmark
- Center for Somatosensory-Motor Interaction, Department of Health Sciences and Technology, Faculty of Medicine , Aalborg University , Aalborg , Denmark
| | - Kelun Wang
- Center for Somatosensory-Motor Interaction, Department of Health Sciences and Technology, Faculty of Medicine , Aalborg University , Aalborg , Denmark
| | - Brian E. Cairns
- Center for Neuroplasticity and Pain, SMI, Department of Health Sciences and Technology, Faculty of Medicine , Aalborg University , Aalborg , Denmark
- Faculty of Pharmaceutical Sciences , University of British Columbia , Vancouver , Canada
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Marine Toxins and Nociception: Potential Therapeutic Use in the Treatment of Visceral Pain Associated with Gastrointestinal Disorders. Toxins (Basel) 2019; 11:toxins11080449. [PMID: 31370176 PMCID: PMC6723473 DOI: 10.3390/toxins11080449] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 07/24/2019] [Accepted: 07/26/2019] [Indexed: 12/12/2022] Open
Abstract
Visceral pain, of which the pathogenic basis is currently largely unknown, is a hallmark symptom of both functional disorders, such as irritable bowel syndrome, and inflammatory bowel disease. Intrinsic sensory neurons in the enteric nervous system and afferent sensory neurons of the dorsal root ganglia, connecting with the central nervous system, represent the primary neuronal pathways transducing gut visceral pain. Current pharmacological therapies have several limitations, owing to their partial efficacy and the generation of severe adverse effects. Numerous cellular targets of visceral nociception have been recognized, including, among others, channels (i.e., voltage-gated sodium channels, VGSCs, voltage-gated calcium channels, VGCCs, Transient Receptor Potential, TRP, and Acid-sensing ion channels, ASICs) and neurotransmitter pathways (i.e., GABAergic pathways), which represent attractive targets for the discovery of novel drugs. Natural biologically active compounds, such as marine toxins, able to bind with high affinity and selectivity to different visceral pain molecular mediators, may represent a useful tool (1) to improve our knowledge of the physiological and pathological relevance of each nociceptive target, and (2) to discover therapeutically valuable molecules. In this review we report the most recent literature describing the effects of marine toxin on gastrointestinal visceral pain pathways and the possible clinical implications in the treatment of chronic pain associated with gut diseases.
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Loeza-Alcocer E, McPherson TP, Gold MS. Peripheral GABA receptors regulate colonic afferent excitability and visceral nociception. J Physiol 2019; 597:3425-3439. [PMID: 31077379 DOI: 10.1113/jp278025] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/10/2019] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS While the presence of GABA receptors on primary afferents has been well described, most functional analyses have focused on the regulation of transmitter release from central terminals and/or signalling in the sensory neuron cell body. Evidence that GABA receptors are transported to peripheral terminals and that there are several sources of GABA in the colon raise the possibility that GABA signalling in the periphery may influence colonic afferent excitability. GABAA and GABAB are present and functional in the colon, where exogenous agonists decrease the excitability of colonic afferents and suppress visceral nociception. Endogenous GABA release within the colon is sufficient to establish the resting excitability of colonic afferents as well as the behavioural response to noxious stimulation of the colon, primarily via GABAA receptors. Peripheral GABA receptors may serve as a viable target for the treatment of visceral pain. ABSTRACT It is well established that GABA receptors at the central terminals of primary afferent fibres regulate afferent input to the superficial dorsal horn. However, the extent to which peripheral GABA signalling may also regulate afferent input remains to be determined. The colon was used to explore this issue because of the numerous endogenous sources of GABA that have been described in this tissue. The influence of GABA signalling on colonic afferent excitability was assessed in an ex vivo mouse colorectum pelvic nerve preparation where test compounds were applied to the receptive field. The visceromotor response (VMR) evoked by noxious colorectal distension was used to assess the impact of GABA signalling on visceral nociception, where test compounds were applied directly to the colon. Application of either GABAA or GABAB receptor agonists attenuated the colonic afferent response to colon stretch. Conversely, GABAA and GABAB receptor antagonists increased the stretch response. However, while the noxious distension-induced VMR was attenuated in the presence of GABAA and GABAB receptor agonists, the VMR was only consistently increased by GABAA receptor antagonists. These results suggest that GABA receptors are present and functional in the peripheral terminals of colonic afferents and activation of these receptors via endogenous GABA release contributes to the establishment of colonic afferent excitability and visceral nociception. These results suggest that increasing peripheral GABA receptor signalling could be used to treat visceral pain.
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Affiliation(s)
- Emanuel Loeza-Alcocer
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Thomas P McPherson
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Michael S Gold
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Contribution of membrane receptor signalling to chronic visceral pain. Int J Biochem Cell Biol 2018; 98:10-23. [DOI: 10.1016/j.biocel.2018.02.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 02/15/2018] [Accepted: 02/19/2018] [Indexed: 12/18/2022]
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Lyubashina O, Sivachenko I. The 5-HT 4 receptor-mediated inhibition of visceral nociceptive neurons in the rat caudal ventrolateral medulla. Neuroscience 2017; 359:277-288. [DOI: 10.1016/j.neuroscience.2017.07.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 03/26/2017] [Accepted: 07/17/2017] [Indexed: 12/23/2022]
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Kannampalli P, Poli SM, Boléa C, Sengupta JN. Analgesic effect of ADX71441, a positive allosteric modulator (PAM) of GABA B receptor in a rat model of bladder pain. Neuropharmacology 2017; 126:1-11. [PMID: 28823612 DOI: 10.1016/j.neuropharm.2017.08.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 07/26/2017] [Accepted: 08/16/2017] [Indexed: 01/12/2023]
Abstract
Therapeutic use of GABAB receptor agonists for conditions like chronic abdominal pain, overactive bladder (OAB) and gastroesophageal reflux disease (GERD) is severely affected by poor blood-brain barrier permeability and potential side effects. ADX71441 is a novel positive allosteric modulator (PAM) of the GABAB receptor that has shown encouraging results in pre-clinical models of anxiety, pain, OAB and alcohol addiction. The present study investigates the analgesic effect of ADX71441 to noxious stimulation of the urinary bladder and colon in rats. In female Sprague-Dawley rats, systemic (i.p), but not intrathecal (i.t), administration of ADX71441 produced a dose-dependent decrease in viscero-motor response (VMR) to graded urinary bladder distension (UBD) and colorectal distension (CRD). Additionally, intra-cerebroventricular (i.c.v.) administration of ADX71441 significantly decreased the VMRs to noxious UBD. In electrophysiology experiments, the drug did not attenuate the responses of UBD-sensitive pelvic nerve afferent (PNA) fibers to UBD. In contrast, ADX71441 significantly decreased the responses of UBD-responsive lumbosacral (LS) spinal neurons in spinal intact rats. However, ADX71441 did not attenuate these LS neurons in cervical (C1-C2) spinal transected rats. During cystometrogram (CMG) recordings, ADX71441 (i.p.) significantly decreased the VMR to slow infusion without affecting the number of voiding contraction. These results indicate that ADX71441 modulate bladder nociception via its effect at the supra-spinal sites without affecting the normal bladder motility and micturition reflex in naïve adult rats.
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Affiliation(s)
- Pradeep Kannampalli
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Sonia-Maria Poli
- Addex Therapeutics, 14 Chemin des Aulx, CH-1228 Plan-les-Ouates, Geneva, Switzerland
| | - Christelle Boléa
- Addex Therapeutics, 14 Chemin des Aulx, CH-1228 Plan-les-Ouates, Geneva, Switzerland
| | - Jyoti N Sengupta
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Pediatric Gastroenterology, Medical College of Wisconsin, Milwaukee, WI, USA.
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Castro J, Harrington AM, Garcia-Caraballo S, Maddern J, Grundy L, Zhang J, Page G, Miller PE, Craik DJ, Adams DJ, Brierley SM. α-Conotoxin Vc1.1 inhibits human dorsal root ganglion neuroexcitability and mouse colonic nociception via GABA B receptors. Gut 2017; 66:1083-1094. [PMID: 26887818 PMCID: PMC5532460 DOI: 10.1136/gutjnl-2015-310971] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 12/22/2015] [Accepted: 01/14/2016] [Indexed: 01/29/2023]
Abstract
OBJECTIVE α-Conotoxin Vc1.1 is a small disulfide-bonded peptide from the venom of the marine cone snail Conus victoriae. Vc1.1 has antinociceptive actions in animal models of neuropathic pain, but its applicability to inhibiting human dorsal root ganglion (DRG) neuroexcitability and reducing chronic visceral pain (CVP) is unknown. DESIGN We determined the inhibitory actions of Vc1.1 on human DRG neurons and on mouse colonic sensory afferents in healthy and chronic visceral hypersensitivity (CVH) states. In mice, visceral nociception was assessed by neuronal activation within the spinal cord in response to noxious colorectal distension (CRD). Quantitative-reverse-transcription-PCR, single-cell-reverse-transcription-PCR and immunohistochemistry determined γ-aminobutyric acid receptor B (GABABR) and voltage-gated calcium channel (CaV2.2, CaV2.3) expression in human and mouse DRG neurons. RESULTS Vc1.1 reduced the excitability of human DRG neurons, whereas a synthetic Vc1.1 analogue that is inactive at GABABR did not. Human DRG neurons expressed GABABR and its downstream effector channels CaV2.2 and CaV2.3. Mouse colonic DRG neurons exhibited high GABABR, CaV2.2 and CaV2.3 expression, with upregulation of the CaV2.2 exon-37a variant during CVH. Vc1.1 inhibited mouse colonic afferents ex vivo and nociceptive signalling of noxious CRD into the spinal cord in vivo, with greatest efficacy observed during CVH. A selective GABABR antagonist prevented Vc1.1-induced inhibition, whereas blocking both CaV2.2 and CaV2.3 caused inhibition comparable with Vc1.1 alone. CONCLUSIONS Vc1.1-mediated activation of GABABR is a novel mechanism for reducing the excitability of human DRG neurons. Vc1.1-induced activation of GABABR on the peripheral endings of colonic afferents reduces nociceptive signalling. The enhanced antinociceptive actions of Vc1.1 during CVH suggest it is a novel candidate for the treatment for CVP.
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Affiliation(s)
- Joel Castro
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Andrea M Harrington
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Sonia Garcia-Caraballo
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Jessica Maddern
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Luke Grundy
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | | | - Guy Page
- Anabios, San Diego, California, USA
| | | | - David J Craik
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
| | - David J Adams
- Illawarra Health & Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Stuart M Brierley
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
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Kannampalli P, Babygirija R, Zhang J, Poe MM, Li G, Cook JM, Shaker R, Banerjee B, Sengupta JN. Neonatal bladder inflammation induces long-term visceral pain and altered responses of spinal neurons in adult rats. Neuroscience 2017; 346:349-364. [PMID: 28126369 DOI: 10.1016/j.neuroscience.2017.01.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 01/09/2017] [Accepted: 01/11/2017] [Indexed: 12/31/2022]
Abstract
Painful events early in life have been shown to increase the incidence of interstitial cystitis/painful bladder syndrome in adulthood. However, the intrinsic mechanism is not well studied. We previously reported that neonatal bladder inflammation causes chronic visceral hypersensitivity along with molecular disruption of spinal GABAergic system in rats. The present study investigates whether these molecular changes affect the integrative function and responses of bladder-sensitive primary afferent and spinal neurons. Neonatal bladder inflammation was induced by intravesicular injection of zymosan during postnatal (P) days 14-16. In adulthood (P60), the viscero-motor response (VMR) to visceral stimuli was significantly inhibited by intrathecal (i.t) HZ166 (GABAAα-2 agonist) only in neonatally saline-treated, but not in neonatally zymosan-treated rats. HZ166 significantly inhibited the responses of bladder-responsive lumbosacral (LS) spinal neurons to urinary bladder distension (UBD) and slow infusion (SI) in neonatally saline-treated rats. Similar results were also observed in naïve adult rats where HZ166 produced significant inhibition of bladder-responsive spinal neurons. However, HZ166 did not inhibit responses of UBD-responsive spinal neurons from neonatally zymosan-treated rats. The drug did not attenuate the responses of UBD-sensitive pelvic nerve afferent (PNA) fibers to UBD and SI in either group of rats tested. Immunohistochemical studies showed a significantly lower level of GABAAα-2 receptor expression in the LS spinal cord of neonatally zymosan-treated rats compared to saline-treated rats. These findings indicate that neonatal bladder inflammation leads to functional and molecular alteration of spinal GABAAα-2 receptor subtypes, which may result in chronic visceral hyperalgesia in adulthood.
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Affiliation(s)
- Pradeep Kannampalli
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Reji Babygirija
- Department of Pediatric Gastroenterology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jiang Zhang
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Michael M Poe
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Guanguan Li
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Reza Shaker
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Banani Banerjee
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jyoti N Sengupta
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Pediatric Gastroenterology, Medical College of Wisconsin, Milwaukee, WI, USA.
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Darbaky Y, Evrard B, Patrier S, Falenta J, Garcin S, Tridon A, Dapoigny M, Silberberg C, Nivoliez A, Diop L. Oral probiotic treatment of Lactobacillus rhamnosus Lcr35 ® prevents visceral hypersensitivity to a colonic inflammation and an acute psychological stress. J Appl Microbiol 2016; 122:188-200. [PMID: 27718511 DOI: 10.1111/jam.13320] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 09/05/2016] [Accepted: 10/05/2016] [Indexed: 12/16/2022]
Abstract
AIMS This study evaluated the efficacy of a repeated oral treatment with two active pharmaceutical ingredients (Lcr Lenio® and Lcr Restituo® ) derivated from the probiotic bacterial strain Lactobacillus rhamnosus Lcr35® in two animal models mimicking different features of irritable bowel syndrome (IBS). IBS is characterized by visceral pain associated with alteration of bowel transit. IBS patients present visceral hypersensitivity with peripheral and central origins. METHODS AND RESULTS The injection of 2,4,6-trinitrobenzenesulfonic acid (TNBS) into the proximal colon as well as an acute partial restraint stress (PRS) produces colonic hypersensitivity measured in conscious rats by a decrease in pain threshold in response to distal colonic distension. Visceral hypersensitivity was produced by injection of TNBS 7 days before colonic distension or by acute PRS on testing day. Treatments were performed once a day during eight consecutive days. CONCLUSIONS This study indicates that an 8-day probiotic treatment (Lcr Lenio and Lcr Restituo) produces an antihypersensitivity activity in both TNBS and PRS visceral pain models. As this probiotic strain attenuates peripherally and centrally induced visceral hypersensitivity in rats, it may be active in treatment of IBS symptoms. An immunomodulatory effect of the probiotics was highlighted in the TNBS model on the IL-23 secretion, suggesting a mechanism of action involving a regulation of the local IL-23/Th17 immune activation. SIGNIFICANCE AND IMPACT OF THE STUDY Two formulas of Lcr35® probiotic strain show very encouraging results for the treatment of IBS patients. Further studies are needed to better understand the role and mechanisms of probiotics on the pathogenesis of IBS.
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Affiliation(s)
| | - B Evrard
- Laboratoire d'Immunologie, Université d'Auvergne-Clermont 1, Clermont-Ferrand, France
| | - S Patrier
- Département Recherche et Développement-Biose®, Arpajon-sur-Cère, France
| | - J Falenta
- Laboratoire d'Immunologie, Université d'Auvergne-Clermont 1, Clermont-Ferrand, France
| | - S Garcin
- Laboratoire d'Immunologie, Université d'Auvergne-Clermont 1, Clermont-Ferrand, France
| | - A Tridon
- Laboratoire d'Immunologie, Université d'Auvergne-Clermont 1, Clermont-Ferrand, France
| | - M Dapoigny
- Médecine Digestive, Centre Hospitalier Universitaire (CHU) Estaing, CHU Clermont Université, Clermont-Ferrand, France
| | | | - A Nivoliez
- Département Recherche et Développement-Biose®, Arpajon-sur-Cère, France
| | - L Diop
- ANS Biotech, Riom, France
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Kannampalli P, Sengupta JN. Role of principal ionotropic and metabotropic receptors in visceral pain. J Neurogastroenterol Motil 2015; 21:147-58. [PMID: 25843070 PMCID: PMC4398235 DOI: 10.5056/jnm15026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 02/24/2015] [Accepted: 03/26/2015] [Indexed: 12/13/2022] Open
Abstract
Visceral pain is the most common form of pain caused by varied diseases and a major reason for patients to seek medical consultation. It also leads to a significant economic burden due to workdays lost and reduced productivity. Further, long-term use of non-specific medications is also associated with side effects affecting the quality of life. Despite years of extensive research and the availability of several therapeutic options, management of patients with chronic visceral pain is often inadequate, resulting in frustration for both patients and physicians. This is, most likely, because the mechanisms associated with chronic visceral pain are different from those of acute pain. Accumulating evidence from years of research implicates several receptors and ion channels in the induction and maintenance of central and peripheral sensitization during chronic pain states. Understanding the specific role of these receptors will facilitate to capitalize on their unique properties to augment the therapeutic efficacy while at the same time minimizing unwanted side effects. The aim of this review is to provide a concise review of the recent literature that reports on the role of principal ionotropic receptors and metabotropic receptors in the modulation visceral pain. We also include an overview of the possibility of these receptors as potential new targets for the treatment of chronic visceral pain conditions.
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Affiliation(s)
- Pradeep Kannampalli
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jyoti N Sengupta
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
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Moloney RD, O'Mahony SM, Dinan TG, Cryan JF. Stress-induced visceral pain: toward animal models of irritable-bowel syndrome and associated comorbidities. Front Psychiatry 2015; 6:15. [PMID: 25762939 PMCID: PMC4329736 DOI: 10.3389/fpsyt.2015.00015] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 01/28/2015] [Indexed: 12/12/2022] Open
Abstract
Visceral pain is a global term used to describe pain originating from the internal organs, which is distinct from somatic pain. It is a hallmark of functional gastrointestinal disorders such as irritable-bowel syndrome (IBS). Currently, the treatment strategies targeting visceral pain are unsatisfactory, with development of novel therapeutics hindered by a lack of detailed knowledge of the underlying mechanisms. Stress has long been implicated in the pathophysiology of visceral pain in both preclinical and clinical studies. Here, we discuss the complex etiology of visceral pain reviewing our current understanding in the context of the role of stress, gender, gut microbiota alterations, and immune functioning. Furthermore, we review the role of glutamate, GABA, and epigenetic mechanisms as possible therapeutic strategies for the treatment of visceral pain for which there is an unmet medical need. Moreover, we discuss the most widely described rodent models used to model visceral pain in the preclinical setting. The theory behind, and application of, animal models is key for both the understanding of underlying mechanisms and design of future therapeutic interventions. Taken together, it is apparent that stress-induced visceral pain and its psychiatric comorbidities, as typified by IBS, has a multifaceted etiology. Moreover, treatment strategies still lag far behind when compared to other pain modalities. The development of novel, effective, and specific therapeutics for the treatment of visceral pain has never been more pertinent.
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Affiliation(s)
- Rachel D Moloney
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork , Cork , Ireland
| | - Siobhain M O'Mahony
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork , Cork , Ireland ; Department of Anatomy and Neuroscience, University College Cork , Cork , Ireland
| | - Timothy G Dinan
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork , Cork , Ireland ; Department of Psychiatry, University College Cork , Cork , Ireland
| | - John F Cryan
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Biosciences Institute, University College Cork , Cork , Ireland ; Department of Anatomy and Neuroscience, University College Cork , Cork , Ireland
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Analgesic effect of minocycline in rat model of inflammation-induced visceral pain. Eur J Pharmacol 2014; 727:87-98. [PMID: 24485889 DOI: 10.1016/j.ejphar.2014.01.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 01/08/2014] [Accepted: 01/12/2014] [Indexed: 12/30/2022]
Abstract
The present study investigates the analgesic effect of minocycline, a semi-synthetic tetracycline antibiotic, in a rat model of inflammation-induced visceral pain. Inflammation was induced in male rats by intracolonic administration of tri-nitrobenzenesulphonic acid (TNBS). Visceral hyperalgesia was assessed by comparing the viscero-motor response (VMR) to graded colorectal distension (CRD) prior and post 7 days after TNBS treatment. Electrophysiology recordings from CRD-sensitive pelvic nerve afferents (PNA) and lumbo-sacral (LS) spinal neurons were performed in naïve and inflamed rats. Colonic inflammation produced visceral hyperalgesia characterized by increase in the VMRs to CRD accompanied with simultaneous activation of microglia in the spinal cord and satellite glial cells (SGCs) in the dorsal root ganglions (DRGs). Selectively inhibiting the glial activation following inflammation by araC (Arabinofuranosyl Cytidine) prevented the development of visceral hyperalgesia. Intrathecal minocycline significantly attenuated the VMR to CRD in inflamed rats, whereas systemic minocycline produced a delayed effect. In electrophysiology experiments, minocycline significantly attenuated the mechanotransduction of CRD-sensitive PNAs and the responses of CRD-sensitive LS spinal neurons in TNBS-treated rats. While the spinal effect of minocycline was observed within 5min of administration, systemic injection of the drug produced a delayed effect (60min) in inflamed rats. Interestingly, minocycline did not exhibit analgesic effect in naïve, non-inflamed rats. The results demonstrate that intrathecal injection of minocycline can effectively attenuate inflammation-induced visceral hyperalgesia. Minocycline might as well act on neuronal targets in the spinal cord of inflamed rats, in addition to the widely reported glial inhibitory action to produce analgesia.
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Blackshaw LA, Brierley SM. Emerging receptor target in the pharmacotherapy of irritable bowel syndrome with constipation. Expert Rev Gastroenterol Hepatol 2013; 7:15-9. [PMID: 23859756 DOI: 10.1586/17474124.2013.820045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Preclinical experiments in rodent models have recently provided new information on the mechanisms underlying pain sensation in chronic visceral hypersensitivity, as well as insights into the mechanism of action of new drugs targeting abdominal pain in irritable bowel syndrome (IBS). This article describes the evidence base supporting the role of guanylate cyclase C (GC-C) activation in the modulation of gastrointestinal transit and, in particular, in visceral hypersensitivity. We propose that GC-C activation represents an important emerging target for pharmacotherapy in IBS with constipation (IBS-C), particularly given the recent regulatory approval of the GC-C agonist linaclotide as a treatment for IBS-C. More specifically, we address the following questions: "How is pain transmitted from the colon?"; "How is abdominal pain increased in IBS-C?"; "How can we reduce IBS-related abdominal pain - what drugs have been developed?"; "Does linaclotide reduce abdominal pain in animals and humans?"; and "How does linaclotide reduce abdominal pain?".
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Affiliation(s)
- L Ashley Blackshaw
- Nerve-Gut Research Laboratory, Discipline of Medicine, Faculty of Health Sciences, University of Adelaide, Adelaide, Australia.
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Davis MP. Drug management of visceral pain: concepts from basic research. PAIN RESEARCH AND TREATMENT 2012; 2012:265605. [PMID: 22619712 PMCID: PMC3348642 DOI: 10.1155/2012/265605] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 02/13/2012] [Indexed: 12/24/2022]
Abstract
Visceral pain is experienced by 40% of the population, and 28% of cancer patients suffer from pain arising from intra- abdominal metastasis or from treatment. Neuroanatomy of visceral nociception and neurotransmitters, receptors, and ion channels that modulate visceral pain are qualitatively or quantitatively different from those that modulate somatic and neuropathic pain. Visceral pain should be recognized as distinct pain phenotype. TRPV1, Na 1.8, and ASIC3 ion channels and peripheral kappa opioid receptors are important mediators of visceral pain. Mu agonists, gabapentinoids, and GABAB agonists reduce pain by binding to central receptors and channels. Combinations of analgesics and adjuvants in animal models have supra-additive antinociception and should be considered in clinical trials. This paper will discuss the neuroanatomy, receptors, ion channels, and neurotransmitters important to visceral pain and provide a basic science rationale for analgesic trials and management.
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Affiliation(s)
- Mellar P. Davis
- Cleveland Clinic Lerner School of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA
- Solid Tumor Division, Harry R. Horvitz Center for Palliative Medicine, Taussig Cancer Institute, USA
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17
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Kurjak M, Fichna J, Harbarth J, Sennefelder A, Allescher HD, Schusdziarra V, Storr M, Otto B. Effect of GABA-ergic mechanisms on synaptosomal NO synthesis and the nitrergic component of NANC relaxation in rat ileum. Neurogastroenterol Motil 2011; 23:e181-90. [PMID: 21414101 DOI: 10.1111/j.1365-2982.2011.01688.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND γ-Aminobutyric acid (GABA) acts on specific neural receptors [A, B and C(Aρ)] to modulate gastrointestinal function. The precise role of GABA receptor activation in the regulation of presynaptic nitric oxide (NO) synthesis in nerve terminals is unknown. METHODS Rat ileal nerve terminals were isolated by differential centrifugation. Nitric oxide synthesis was analysed using a L-[(3) H]arginine assay. In vitro studies were performed under non-adrenergic non-cholinergic (NANC) conditions on isolated ileal segments. KEY RESULTS γ-Aminobutyric acid inhibited NO synthesis significantly (n = 6, P < 0.05) [(fmol mg(-1) min(-1)) control: 27.7 ± 1.5, 10(-6) mol L(-1): 19.7 ± 1.3; 10(-5) mol L(-1): 17.5 ± 3.0]. This effect was antagonized by the GABA A receptor antagonist bicuculline and the GABA C receptor antagonist (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA), but not by the GABA B receptor antagonist SCH 50911. The GABA A receptor agonist muscimol [(fmol mg(-1) min(-1)) control: 27.6 ± 1.0, 10(-6) mol L(-1): 19.1 ± 1.7, n = 5, P < 0.05] and the GABA C receptor agonist cis-4-aminocrotonic acid (CACA) [(fmol mg(-1) min(-1)) control: 29.5 ± 3.2, 10(-3) mol L(-1): 20.3 ± 2.5, n = 6, P < 0.05], mimicked the GABA-effect, whereas the GABA B agonist baclofen was ineffective. Bicuculline reversed the inhibitory effect of muscimol, TPMPA antagonized the effect of CACA. In functional experiments the GABA A and C receptor agonists reduced the NANC relaxation induced by electrical field stimulation in rat ileum by about 40%. After NOS-inhibition by Nε-nitro-L-arginine methyl ester (L-NAME) the GABA A receptor agonist had no effect, whereas the GABA C receptor agonist still showed a residual response. CONCLUSIONS & INFERENCES γ-Aminobutyric acid inhibits neural NO synthesis in rat ileum by GABA A and GABA C(Aρ) receptor-mediated mechanisms.
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Affiliation(s)
- M Kurjak
- Endooffice Abdomen, Munich, Germany.
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Hyland NP, Cryan JF. A Gut Feeling about GABA: Focus on GABA(B) Receptors. Front Pharmacol 2010; 1:124. [PMID: 21833169 PMCID: PMC3153004 DOI: 10.3389/fphar.2010.00124] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2010] [Accepted: 09/07/2010] [Indexed: 12/15/2022] Open
Abstract
γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the body and hence GABA-mediated neurotransmission regulates many physiological functions, including those in the gastrointestinal (GI) tract. GABA is located throughout the GI tract and is found in enteric nerves as well as in endocrine-like cells, implicating GABA as both a neurotransmitter and an endocrine mediator influencing GI function. GABA mediates its effects via GABA receptors which are either ionotropic GABA(A) or metabotropic GABA(B). The latter which respond to the agonist baclofen have been least characterized, however accumulating data suggest that they play a key role in GI function in health and disease. Like GABA, GABA(B) receptors have been detected throughout the gut of several species in the enteric nervous system, muscle, epithelial layers as well as on endocrine-like cells. Such widespread distribution of this metabotropic GABA receptor is consistent with its significant modulatory role over intestinal motility, gastric emptying, gastric acid secretion, transient lower esophageal sphincter relaxation and visceral sensation of painful colonic stimuli. More intriguing findings, the mechanisms underlying which have yet to be determined, suggest GABA(B) receptors inhibit GI carcinogenesis and tumor growth. Therefore, the diversity of GI functions regulated by GABA(B) receptors makes it a potentially useful target in the treatment of several GI disorders. In light of the development of novel compounds such as peripherally acting GABA(B) receptor agonists, positive allosteric modulators of the GABA(B) receptor and GABA producing enteric bacteria, we review and summarize current knowledge on the function of GABA(B) receptors within the GI tract.
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Affiliation(s)
- Niall P Hyland
- Alimentary Pharmabiotic Centre and Department of Pharmacology and Therapeutics, University College Cork Cork, Ireland
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Mickle A, Sood M, Zhang Z, Shahmohammadi G, Sengupta JN, Miranda A. Antinociceptive effects of melatonin in a rat model of post-inflammatory visceral hyperalgesia: a centrally mediated process. Pain 2010; 149:555-564. [PMID: 20413219 DOI: 10.1016/j.pain.2010.03.030] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 03/18/2010] [Accepted: 03/22/2010] [Indexed: 12/15/2022]
Abstract
Previous reports suggest that melatonin may play an important role in visceral nociception and neurogenic inflammation. We aimed to examine the role of melatonin on visceral hypersensitivity and to explore the site of action using a rat model of post-inflammatory visceral hyperalgesia. In all rats, a baseline viscero-motor response (VMR) to graded colorectal distension (CRD; 10-60mmHg) was recorded prior and 1 week following tri-nitrobenzenesulfonic acid (TNBS) induced colonic inflammation. Melatonin (30, 45 or 60mg/kg, ip) was given 20min before testing the VMR in naïve and TNBS-treated rats. Extracellular single-unit recordings were made from CRD-sensitive pelvic nerve afferent (PNA) fibers and lumbosacral (LS) spinal neurons in TNBS-treated animals. The effect of melatonin (60mg/kg) was examined on responses of PNAs and spinal neurons to graded CRD. In separate experiments, luzindole (non-specific MT(1)/MT(2) receptor antagonist) or naltrexone (non-specific opiod receptor antagonist) was injected prior to melatonin. Following TNBS, there was a significant increase in the VMR to CRD compared to baseline. This increase was attenuated by melatonin (60mg/kg) at pressures >20mmHg. The same dose of melatonin had no effect on the VMR in naïve animals. In TNBS-treated rats, melatonin significantly attenuated the responses of CRD-sensitive spinal neurons to CRD, but had no effect in spinal transected rats or PNA fibers. Both luzindole and naltrexone blocked melatonin's effect on the VMR and LS spinal neurons. Results indicate melatonin's antinociceptive effects are not via a peripheral site of action but rather a supra-spinal process linked to the central opioidergic system.
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Affiliation(s)
- Aaron Mickle
- Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Gangadharan V, Agarwal N, Brugger S, Tegeder I, Bettler B, Kuner R, Kurejova M. Conditional gene deletion reveals functional redundancy of GABAB receptors in peripheral nociceptors in vivo. Mol Pain 2009; 5:68. [PMID: 19925671 PMCID: PMC2785766 DOI: 10.1186/1744-8069-5-68] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 11/19/2009] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND gamma-aminobutyric acid (GABA) is an important inhibitory neurotransmitter which mainly mediates its effects on neurons via ionotropic (GABA(A)) and metabotropic (GABA(B)) receptors. GABA(B) receptors are widely expressed in the central and the peripheral nervous system. Although there is evidence for a key function of GABA(B) receptors in the modulation of pain, the relative contribution of peripherally- versus centrally-expressed GABA(B) receptors is unclear. RESULTS In order to elucidate the functional relevance of GABA(B) receptors expressed in peripheral nociceptive neurons in pain modulation we generated and analyzed conditional mouse mutants lacking functional GABA(B1) subunit specifically in nociceptors, preserving expression in the spinal cord and brain (SNS-GABA(B1)-/- mice). Lack of the GABA(B1) subunit precludes the assembly of functional GABA(B) receptor. We analyzed SNS-GABA(B1)-/- mice and their control littermates in several models of acute and neuropathic pain. Electrophysiological studies on peripheral afferents revealed higher firing frequencies in SNS-GABA(B1)-/- mice compared to corresponding control littermates. However no differences were seen in basal nociceptive sensitivity between these groups. The development of neuropathic and chronic inflammatory pain was similar across the two genotypes. The duration of nocifensive responses evoked by intraplantar formalin injection was prolonged in the SNS-GABAB(1)-/- animals as compared to their control littermates. Pharmacological experiments revealed that systemic baclofen-induced inhibition of formalin-induced nociceptive behaviors was not dependent upon GABA(B1) expression in nociceptors. CONCLUSION This study addressed contribution of GABA(B) receptors expressed on primary afferent nociceptive fibers to the modulation of pain. We observed that neither the development of acute and chronic pain nor the analgesic effects of a systematically-delivered GABA(B) agonist was significantly changed upon a specific deletion of GABA(B) receptors from peripheral nociceptive neurons in vivo. This lets us conclude that GABA(B) receptors in the peripheral nervous system play a less important role than those in the central nervous system in the regulation of pain.
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Affiliation(s)
- Vijayan Gangadharan
- Pharmacology Institute, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.
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21
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Roles of gastro-oesophageal afferents in the mechanisms and symptoms of reflux disease. Handb Exp Pharmacol 2009:227-57. [PMID: 19655109 DOI: 10.1007/978-3-540-79090-7_7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Oesophageal pain is one of the most common reasons for physician consultation and/or seeking medication. It is most often caused by acid reflux from the stomach, but can also result from contractions of the oesophageal muscle. Different forms of pain are evoked by oesophageal acid, including heartburn and non-cardiac chest pain, but the basic mechanisms and pathways by which these are generated remain to be elucidated. Both vagal and spinal afferent pathways are implicated by basic research. The sensitivity of afferent fibres within these pathways may become altered after acid-induced inflammation and damage, but the severity of symptoms in humans does not necessarily correlate with the degree of inflammation. Gastro-oesophageal reflux disease (GORD) is caused by transient relaxations of the lower oesophageal sphincter, which are triggered by activation of gastric vagal mechanoreceptors. Vagal afferents are therefore an emerging therapeutic target for GORD. Pain in the absence of excess acid reflux remains a major challenge for treatment.
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Abstract
The mechanism of visceral pain is still less understood compared with that of somatic pain. This is primarily due to the diverse nature of visceral pain compounded by multiple factors such as sexual dimorphism, psychological stress, genetic trait, and the nature of predisposed disease. Due to multiple contributing factors there is an enormous challenge to develop animal models that ideally mimic the exact disease condition. In spite of that, it is well recognized that visceral hypersensitivity can occur due to (1) sensitization of primary sensory afferents innervating the viscera, (2) hyperexcitability of spinal ascending neurons (central sensitization) receiving synaptic input from the viscera, and (3) dysregulation of descending pathways that modulate spinal nociceptive transmission. Depending on the type of stimulus condition, different neural pathways are involved in chronic pain. In early-life psychological stress such as maternal separation, chronic pain occurs later in life due to dysregulation of the hypothalamic-pituitary-adrenal axis and significant increase in corticotrophin releasing factor (CRF) secretion. In contrast, in early-life inflammatory conditions such as colitis and cystitis, there is dysregulation of the descending opioidergic system that results excessive pain perception (i.e., visceral hyperalgesia). Functional bowel disorders and chronic pelvic pain represent unexplained pain that is not associated with identifiable organic diseases. Often pain overlaps between two organs and approximately 35% of patients with chronic pelvic pain showed significant improvement when treated for functional bowel disorders. Animal studies have documented that two main components such as (1) dichotomy of primary afferent fibers innervating two pelvic organs and (2) common convergence of two afferent fibers onto a spinal dorsal horn are contributing factors for organ-to-organ pain overlap. With reports emerging about the varieties of peptide molecules involved in the pathological conditions of visceral pain, it is expected that better therapy will be achieved relatively soon to manage chronic visceral pain.
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De Schepper HU, De Winter BY, Van Nassauw L, Timmermans JP, Herman AG, Pelckmans PA, De Man JG. TRPV1 receptors on unmyelinated C-fibres mediate colitis-induced sensitization of pelvic afferent nerve fibres in rats. J Physiol 2008; 586:5247-58. [PMID: 18755744 DOI: 10.1113/jphysiol.2008.159731] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Patients with inflammatory bowel disease often suffer from gastrointestinal motility and sensitivity disorders. The aim of the current study was to investigate the role of transient receptor potential of the vanilloid type 1 (TRPV1) receptors in the pathophysiology of colitis-induced pelvic afferent nerve sensitization. Trinitrobenzene sulphate (TNBS) colitis (7.5 mg, 30% ethanol) was induced in Wistar rats 72 h prior to the experiment. Single-fibre recordings were made from pelvic nerve afferents in the decentralized S1 dorsal root. Fibres responding to colorectal distension (CRD) were identified in controls and rats with TNBS colitis. The effect of the TRPV1 antagonist N-(4-tertiarybutylphenyl)-4-(3-chlorophyridin-2-yl)tetrahydropyrazine-1(2H)carboxamide (BCTC; 0.25-5 mg kg(-1)) or its vehicle (hydroxypropyl-beta-cyclodextrin) was tested on the afferent response to repetitive distensions (60 mmHg). Immunocytochemical staining of TRPV1 and NF200, a marker for A-fibre neurons, was performed in the dorsal root ganglia L6-S1. TNBS colitis significantly increased the response to colorectal distension of pelvic afferent C-fibres. BCTC did not significantly affect the C-fibre response in controls, but normalized the sensitized response in rats with colitis. TNBS colitis increased the spontaneous activity of C-fibres, an effect which was insensitive to administration of BCTC. TNBS colitis had no effect on Adelta-fibres, nor was their activity modulated by BCTC. TNBS colitis caused an immunocytochemical up-regulation of TRPV1 receptors in the cell bodies of pelvic afferent NF200 negative neurons. TRPV1 signalling mediates the colitis-induced sensitization of pelvic afferent C-fibres to CRD, while Adelta-fibres are neither sensitized by colitis nor affected by TRPV1 inhibition.
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Affiliation(s)
- H U De Schepper
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, Faculty of Medicine, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium
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Abstract
The gastrointestinal (GI) tract must balance ostensibly opposite functions. On the one hand, it must undertake the process of digestion and absorption of nutrients. At the same time, the GI tract must protect itself from potential harmful antigenic and pathogenic material. Central to these processes is the ability to 'sense' the mechanical and chemical environment in the gut wall and lumen in order to orchestrate the appropriate response that facilitates nutrient assimilation or the rapid expulsion through diarrhoea and/or vomiting. In this respect, the GI tract is richly endowed with sensory elements that monitor the gut environment. Enteric neurones provide one source of such sensory innervation and are responsible for the ability of the decentralized gut to perform complex reflex functions. Extrinsic afferents not only contribute to this reflex control, but also contribute to homeostatic mechanisms and can give rise to sensations, under certain circumstances. The enteric and extrinsic sensory mechanisms share a number of common features but also some remarkably different properties. The purpose of this review is to summarize current views on sensory processing within both the enteric and extrinsic innervation and to specifically address the pharmacology of nociceptive extrinsic sensory pathways.
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Affiliation(s)
- L A Blackshaw
- Nerve Gut Research Laboratory, Hanson Institute, Royal Adelaide Hospital, University of Adelaide, Adelaide, SA, Australia
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25
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Lynn PA, Olsson C, Zagorodnyuk V, Costa M, Brookes SJH. Rectal intraganglionic laminar endings are transduction sites of extrinsic mechanoreceptors in the guinea pig rectum. Gastroenterology 2003; 125:786-94. [PMID: 12949724 DOI: 10.1016/s0016-5085(03)01050-3] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Vagal afferent mechanoreceptors in the upper gut have recently been identified morphologically as intraganglionic laminar endings (IGLEs), but little is known about the structure of mechanoreceptive endings elsewhere in the gastrointestinal tract. We have morphologically characterized the nerve endings of specialized mechanoreceptors in the rectum. METHODS Extracellular recordings from guinea pig rectal and colonic nerves were made, in vitro, in combination with rapid anterograde transport of biotinamide, to reveal the morphology of recorded fibers. Controlled distentions were used to activate mechanoreceptive afferent units, and von Frey hairs were used to identify their transduction sites. RESULTS Rectal mechanoreceptors were present in high density, had low thresholds, and adapted slowly to maintained distention. Each afferent unit had multiple small (<200 microm diameter) transduction sites ("hot spots") at which they could be activated locally by application of a light von Frey hair (0.08-7 mN). Anterograde dye filling revealed characteristic rectal intraganglionic laminar endings (rIGLEs) in myenteric ganglia, significantly associated with hot spots, comparable to the IGLEs of vagal tension receptors, but smaller and less complex. Afferent fibers with these morphologic and physiologic features could not be recorded from colonic nerves innervating the large bowel proximal to the rectum. CONCLUSIONS The rectum receives a dense afferent innervation by a distinct population of low-threshold, slowly adapting mechanoreceptors with specialized intraganglionic laminar endings (rIGLEs), which are not found more proximally in the colon.
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Affiliation(s)
- Penny A Lynn
- Department of Human Physiology and Centre for Neuroscience, Flinders University, South Australia, Australia
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